Merge pull request #1675 from acqn/ShiftFix

[cc65] Fixed bitwise shift with numeric constant operand(s)

src/cc65/expr.c

@@ -216,8 +216,11 @@ void LimitExprValue (ExprDesc* Expr)
             break;
 
         case T_LONG:
+            Expr->IVal = (int32_t)Expr->IVal;
+            break;
+
         case T_ULONG:
-            /* No need to do anything */
+            Expr->IVal = (uint32_t)Expr->IVal;
             break;
 
         case T_SCHAR:

src/cc65/shiftexpr.c

@@ -64,11 +64,11 @@ void ShiftExpr (struct ExprDesc* Expr)
     CodeMark Mark1;
     CodeMark Mark2;
     token_t Tok;                        /* The operator token */
-    const Type* EffType;                /* Effective lhs type */
     const Type* ResultType;             /* Type of the result */
     unsigned ExprBits;                  /* Bits of the lhs operand */
     unsigned GenFlags;                  /* Generator flags */
     unsigned ltype;
+    int lconst;                         /* Operand is a constant */
     int rconst;                         /* Operand is a constant */
 
 
@@ -92,7 +92,7 @@ void ShiftExpr (struct ExprDesc* Expr)
         NextToken ();
 
         /* Get the type of the result */
-        ResultType = EffType = IntPromotion (Expr->Type);
+        ResultType = IntPromotion (Expr->Type);
 
         /* Prepare the code generator flags */
         GenFlags = TypeOf (ResultType);
@@ -103,7 +103,8 @@ void ShiftExpr (struct ExprDesc* Expr)
         /* Get the lhs on stack */
         GetCodePos (&Mark1);
         ltype = TypeOf (Expr->Type);
-        if (ED_IsConstAbs (Expr)) {
+        lconst = ED_IsConstAbs (Expr);
+        if (lconst) {
             /* Constant value */
             GetCodePos (&Mark2);
             g_push (ltype | CF_CONST, Expr->IVal);
@@ -115,7 +116,7 @@ void ShiftExpr (struct ExprDesc* Expr)
         }
 
         /* Get the right hand side */
-        ExprWithCheck (hie8, &Expr2);
+        MarkedExprWithCheck (hie8, &Expr2);
 
         /* Check the type of the rhs */
         if (!IsClassInt (Expr2.Type)) {
@@ -124,7 +125,7 @@ void ShiftExpr (struct ExprDesc* Expr)
         }
 
         /* Check for a constant right side expression */
-        rconst = ED_IsConstAbs (&Expr2);
+        rconst = ED_IsConstAbs (&Expr2) && ED_CodeRangeIsEmpty (&Expr2);
         if (!rconst) {
 
             /* Not constant, load into the primary */
@@ -154,31 +155,32 @@ void ShiftExpr (struct ExprDesc* Expr)
 
             }
 
-            /* If the shift count is zero, nothing happens */
-            if (Expr2.IVal == 0) {
+            /* If the shift count is zero, nothing happens. If the left hand
+            ** side is a constant, the result is constant.
+            */
+            if (Expr2.IVal == 0 || lconst) {
 
-                /* Result is already in Expr, remove the generated code */
-                RemoveCode (&Mark1);
+                /* Set the type */
+                Expr->Type = ResultType;
 
-                /* Done */
-                goto Next;
-            }
+                if (lconst) {
 
-            /* If the left hand side is a constant, the result is constant */
-            if (ED_IsConstAbs (Expr)) {
+                    /* Evaluate the result */
+                    switch (Tok) {
+                        case TOK_SHL: Expr->IVal <<= Expr2.IVal; break;
+                        case TOK_SHR: Expr->IVal >>= Expr2.IVal; break;
+                        default: /* Shutup gcc */                break;
+                    }
 
-                /* Evaluate the result */
-                switch (Tok) {
-                    case TOK_SHL: Expr->IVal <<= Expr2.IVal; break;
-                    case TOK_SHR: Expr->IVal >>= Expr2.IVal; break;
-                    default: /* Shutup gcc */                break;
+                    /* Limit the calculated value to the range of its type */
+                    LimitExprValue (Expr);
                 }
 
-                /* Both operands are constant, remove the generated code */
+                /* Result is already got, remove the generated code */
                 RemoveCode (&Mark1);
 
                 /* Done */
-                goto Next;
+                continue;
             }
 
             /* If we're shifting an integer or unsigned to the right, the lhs
@@ -188,13 +190,12 @@ void ShiftExpr (struct ExprDesc* Expr)
             ** shift count is zero, we're done.
             */
             if (Tok == TOK_SHR &&
-                IsTypeInt (Expr->Type) &&
+                IsClassInt (Expr->Type) &&
+                SizeOf (Expr->Type) == SIZEOF_INT &&
                 ED_IsLVal (Expr) &&
                 ED_IsLocQuasiConst (Expr) &&
                 Expr2.IVal >= 8) {
 
-                const Type* OldType;
-
                 /* Increase the address by one and decrease the shift count */
                 ++Expr->IVal;
                 Expr2.IVal -= 8;
@@ -202,7 +203,6 @@ void ShiftExpr (struct ExprDesc* Expr)
                 /* Replace the type of the expression temporarily by the
                 ** corresponding char type.
                 */
-                OldType = Expr->Type;
                 if (IsSignUnsigned (Expr->Type)) {
                     Expr->Type = type_uchar;
                 } else {
@@ -215,9 +215,6 @@ void ShiftExpr (struct ExprDesc* Expr)
                 /* Generate again code for the load, this time with the new type */
                 LoadExpr (CF_NONE, Expr);
 
-                /* Reset the type */
-                Expr->Type = OldType;
-
                 /* If the shift count is now zero, we're done */
                 if (Expr2.IVal == 0) {
                     /* Be sure to mark the value as in the primary */
@@ -238,7 +235,6 @@ MakeRVal:
         /* We have an rvalue in the primary now */
         ED_FinalizeRValLoad (Expr);
 
-Next:
         /* Set the type of the result */
         Expr->Type = ResultType;
     }

test/val/bug1675-ub.c

@@ -0,0 +1,60 @@
+/* #1675 - Some UB cases of bit-shifts */
+
+#include <stdio.h>
+
+int unexpected = 0;
+
+void Test_UB(void)
+{
+    {
+        /* UB per standard, lhs expected in cc65: (int)-32768 */
+        if (!((0x4000 << 1) < 0)) {
+            ++unexpected;
+            printf("Expected: (0x4000 << 1) < 0, got lhs: %ld\n", (long)(0x4000 << 1));
+        }
+    }
+
+    {
+        /* UB per standard, lhs expected in cc65: (long)-2147483648L */
+        if (!((0x40000000 << 1) < 0)) {
+            ++unexpected;
+            printf("Expected: (0x40000000 << 1) < 0, got lhs: %ld\n", (long)(0x40000000 << 1));
+        }
+    }
+
+    {
+        /* UB per standard, lhs expected in cc65: (int)-32768 */
+        if (!(((unsigned char)0x80 << 8) < 0)) {
+            ++unexpected;
+            printf("Expected: ((unsigned char)0x80 << 8) < 0, got lhs: %ld\n", (long)((unsigned char)0x80 << 8));
+        }
+    }
+
+    {
+        /* UB per standard, lhs expected in cc65: (int)-32768 */
+        if (!(((short)0x4000L << 1) < 0)) {
+            ++unexpected;
+            printf("Expected: ((short)0x4000L << 1) < 0, got lhs: %ld\n", (long)((short)0x4000L << 1));
+        }
+    }
+
+    {
+        const signed short x = 0x4000;
+        /* UB per standard, lhs expected in cc65: (int)-32768 */
+        if (!((x << 1) < 0)) {
+            ++unexpected;
+            printf("Expected: (x << 1) < 0, got lhs: %ld\n", (long)(x << 1));
+        }
+    }
+}
+
+int main(void)
+{
+    Test_UB();
+
+    if (unexpected != 0) {
+        printf("Unexpected: %d\n", unexpected);
+    }
+
+    return unexpected;
+}

test/val/bug1675.c

@@ -0,0 +1,101 @@
+/* #1675 - Some corner cases of bit-shifts */
+
+#include <stdio.h>
+
+int failures = 0;
+
+void Test_Defined(void)
+{
+    {
+        /* Well-defined per standard, lhs expected in cc65: (int)-256 */
+        if (!(((signed char)0x80 << 1) < 0)) {
+            ++failures;
+            printf("Expected: ((signed char)0x80 << 1) < 0, got lhs: %ld\n", (long)((signed char)0x80 << 1));
+        }
+    }
+
+    {
+        /* Implementation-defined per standard, lhs expected in cc65: (int)-128 */
+        if (!(((signed char)0x80 >> 1 << 1) < 0)) {
+            ++failures;
+            printf("Expected: ((signed char)0x80 >> 1 << 1) < 0, got lhs: %ld\n", (long)((signed char)0x80 >> 1 << 1));
+        }
+    }
+
+    {
+        int x = 0;
+        /* Well-defined per standard, lhs expected in cc65: (int)1 */
+        if (!((1 << (x++, 0)) == 1)) {
+            ++failures;
+            x = 0;
+            printf("Expected: (1 << (x++, 0)) == 1, got lhs: %ld\n", (long)(1 << (x++, 0)));
+        }
+
+        /* Well-defined per standard, lhs expected in cc65: (int)1 */
+        if (!(x == 1)) {
+            ++failures;
+            printf("Expected: (1 << (x++, 0)) == 1 && x == 1, got x: %d\n", x);
+        }
+    }
+
+    {
+        int x = 0, y = 0x100;
+        /* Well-defined per standard, lhs expected in cc65: (int)128 */
+        if (!((y >> (x++, 0) >> 1) == 0x80)) {
+            ++failures;
+            x = 0;
+            printf("Expected: (y >> (x++, 0) >> 1) == 0x80, got lhs: %ld\n", (long)(y >> (x++, 0) >> 1));
+        }
+
+        /* Well-defined per standard, lhs expected in cc65: (int)1 */
+        if (!(x == 1)) {
+            ++failures;
+            printf("Expected: (y >> (x++, 0) >> 1) == 0x80 && x == 1, got x: %d\n", x);
+        }
+    }
+
+    {
+        int x = 0, y = 0x100;
+        /* Well-defined per standard, lhs expected in cc65: (int)1 */
+        if (!((y >> (x++, 8)) == 1)) {
+            ++failures;
+            x = 0;
+            printf("Expected: (y >> (x++, 8)) == 1, got lhs: %ld\n", (long)(y >> (x++, 8)));
+        }
+
+        /* Well-defined per standard, lhs expected in cc65: (int)1 */
+        if (!(x == 1)) {
+            ++failures;
+            printf("Expected: (y >> (x++, 8)) == 1 && x == 1, got x: %d\n", x);
+        }
+    }
+
+    {
+        const signed char x = 0x80;
+        /* Well-defined per standard, lhs expected in cc65: (int)-256 */
+        if (!((x << 1) < 0)) {
+            ++failures;
+            printf("Expected: (x << 1) < 0, got lhs: %ld\n", (long)(x << 1));
+        }
+    }
+
+    {
+        const signed char x = 0x40;
+        /* Well-defined per standard, lhs expected in cc65: (int)128 */
+        if (!((x << 1) >= 0)) {
+            ++failures;
+            printf("Expected: (x << 1) >= 0, got lhs: %ld\n", (long)(x << 1));
+        }
+    }
+}
+
+int main(void)
+{
+    Test_Defined();
+
+    if (failures != 0) {
+        printf("Failures: %d\n", failures);
+    }
+
+    return failures;
+}